Since the development of the modern-day shopping cart, unpaid product has inadvertently exited the retail grocery store via the lower tray of the shopping cart. The reason for this is that as a customer's shopping cart reaches the point-of-sale checkstand, the cashier's view of the lower tray is obstructed by the checkstand; thus, the customer is, in most cases, innocently and unwittingly permitted to exit the premises without declaring the product. Though this flaw is exploited by the dishonest, the more significant problem is the inadvertent error.
A thorough study of this point-of-sale design flaw estimates that the average loss to the retail grocery industry is 85% of the product stored on the lower tray of a shopping cart. The obvious solution might be to simply remove this lower tray; however, the lower tray represents considerable extra revenue by allowing the storage of bulk items such as dog food or cases of soda. Without the lower tray, customers are reluctant to place bulk items in the basket.
Occasionally, the cashier or another store employee may spot the product in the bottom tray after the checkout has been completed. In order to remedy the situation after checkout, the cashier would have to verbally confront the customer. This is potentially embarrassing to both the cashier and the customer, and delays the checkout process. In light of this, cashiers will often not stop a customer after the checkout has been completed for this purpose.
Over the last thirty-five years several systems have been designed and tested in the field. Previous technologies applied in an effort to eliminate this problem used various configurations and components ranging from mirrors and watchers (employees hired to actively watch the lower tray) to infrared sensors with reflectors and shopping cart mounted mechanical linkage devices. Due to the inflexibility and inaccuracy of earlier designs and methods, a true working system was never realized.
Generally speaking, the detection of something on the bottom tray may be described as activation, as it represents the activation of the system in response to something. True activation occurs when the cashier is alerted by the device to the presence of items on the lower tray and requests the customer declare the forgotten items before the financial transaction is completed. This is a desired function of the invention. False activation occurs when the alert triggering mechanism is triggered by something other than the presence of an object on the bottom tray of the shopping cart. It is desirable to minimize or eliminate altogether the number of false activations, giving the cashier confidence in the system and avoiding the embarrassing situation where the cashier asks the customer for the items on the bottom tray when in fact there is nothing on the bottom tray. Non-activation occurs when the intended target is present but not detected.
To date, technologies and applications thereof attempting to eliminate this problem have had limited success for a variety of reasons including variations in shopping cart design or checkstand design, variations in traffic flow at the point of sale, problems with type of technology being used, and the lack of full attention on the part of the cashier.
There have been a number of systems that detected weight on the bottom tray and then activated a signal, but these inventions have either proved unreliable, or have been easily circumvented by inserting an object into the mechanical workings of the system, thereby preventing the activation of the signal.
Large objects have also posed problems for earlier detection systems. On a typical shopping cart, the existing lower tray, in the seated position, rests degraded to the rear of the cart to prevent objects from rolling or sliding off the lower tray in the event of a sudden stop. As a result, the cart's frame, with the tray in the seated or empty state, is the highest point. If an object is large enough, it can straddle the frame without actually touching the lower tray thus defeating these earlier systems.